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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 869 · 40 questions
TalentJR

How to do it in your head (Round, then work): Round each number: 2-digit numbers to the nearest ten, 3-digit numbers to the nearest hundred. Do the easy sum with the round numbers. Choose the option closest to your estimate.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 40 × 46? (a) 200 (b) 20000 (c) 2000
  2. 2.Best estimate of 163 + 516? (a) 900 (b) 700 (c) 500
  3. 3.Best estimate of 22 × 57? (a) 12000 (b) 1200 (c) 120
  4. 4.Best estimate of 139 + 831? (a) 1100 (b) 900 (c) 700
  5. 5.Best estimate of 404 + 295? (a) 700 (b) 500 (c) 900
  6. 6.Best estimate of 247 + 798? (a) 1200 (b) 1000 (c) 800
  7. 7.Best estimate of 24 × 22? (a) 40 (b) 4000 (c) 400
  8. 8.Best estimate of 487 + 322? (a) 1000 (b) 800 (c) 600
  9. 9.Best estimate of 66 × 92? (a) 6300 (b) 630 (c) 63000
  10. 10.Best estimate of 665 + 334? (a) 1000 (b) 800 (c) 1200
  11. 11.Best estimate of 405 + 330? (a) 700 (b) 500 (c) 900
  12. 12.Best estimate of 393 + 847? (a) 1200 (b) 1400 (c) 1000
  13. 13.Best estimate of 32 × 14? (a) 300 (b) 3000 (c) 30
  14. 14.Best estimate of 14 × 91? (a) 90 (b) 900 (c) 9000
  15. 15.Best estimate of 92 × 39? (a) 360 (b) 3600 (c) 36000
  16. 16.Best estimate of 869 + 549? (a) 1400 (b) 1200 (c) 1600
  17. 17.Best estimate of 398 + 601? (a) 1200 (b) 800 (c) 1000
  18. 18.Best estimate of 271 + 574? (a) 1100 (b) 900 (c) 700
  19. 19.Best estimate of 82 × 46? (a) 400 (b) 40000 (c) 4000
  20. 20.Best estimate of 30 × 46? (a) 150 (b) 15000 (c) 1500
  21. 21.Best estimate of 371 + 288? (a) 700 (b) 900 (c) 500
  22. 22.Best estimate of 90 × 53? (a) 4500 (b) 450 (c) 45000
  23. 23.Best estimate of 72 × 88? (a) 6300 (b) 630 (c) 63000
  24. 24.Best estimate of 276 + 631? (a) 700 (b) 1100 (c) 900
  25. 25.Best estimate of 797 + 834? (a) 1800 (b) 1400 (c) 1600
  26. 26.Best estimate of 19 × 56? (a) 12000 (b) 1200 (c) 120
  27. 27.Best estimate of 74 × 30? (a) 21000 (b) 2100 (c) 210
  28. 28.Best estimate of 155 + 782? (a) 1200 (b) 800 (c) 1000
  29. 29.Best estimate of 175 + 584? (a) 800 (b) 1000 (c) 600
  30. 30.Best estimate of 72 × 21? (a) 1400 (b) 140 (c) 14000
  31. 31.Best estimate of 463 + 566? (a) 1300 (b) 900 (c) 1100
  32. 32.Best estimate of 396 + 241? (a) 400 (b) 600 (c) 800
  33. 33.Best estimate of 590 + 663? (a) 1300 (b) 1100 (c) 1500
  34. 34.Best estimate of 742 + 588? (a) 1100 (b) 1500 (c) 1300
  35. 35.Best estimate of 533 + 285? (a) 600 (b) 1000 (c) 800
  36. 36.Best estimate of 333 + 367? (a) 500 (b) 700 (c) 900
  37. 37.Best estimate of 86 × 42? (a) 3600 (b) 360 (c) 36000
  38. 38.Best estimate of 700 + 263? (a) 1000 (b) 800 (c) 1200
  39. 39.Best estimate of 50 × 32? (a) 15000 (b) 150 (c) 1500
  40. 40.Best estimate of 38 × 49? (a) 20000 (b) 2000 (c) 200

Answer key

  1. 2000
  2. 700
  3. 1200
  4. 900
  5. 700
  6. 1000
  7. 400
  8. 800
  9. 6300
  10. 1000
  11. 700
  12. 1200
  13. 300
  14. 900
  15. 3600
  16. 1400
  17. 1000
  18. 900
  19. 4000
  20. 1500
  21. 700
  22. 4500
  23. 6300
  24. 900
  25. 1600
  26. 1200
  27. 2100
  28. 1000
  29. 800
  30. 1400
  31. 1100
  32. 600
  33. 1300
  34. 1300
  35. 800
  36. 700
  37. 3600
  38. 1000
  39. 1500
  40. 2000

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